An apparatus includes an input terminal to receive a radio frequency (RF) signal and to communicate the RF signal to a low noise amplifier (LNA) via an input signal path, and a capacitor attenuator coupled to the input terminal to attenuate the RF signal by a controllable amount and having a first portion controllable to include a used part configured on the input signal path and an unused part coupled between the input signal path and an AC reference node, and a second portion coupled between the LNA and the AC reference node.
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1. A system comprising: an antenna to receive a radio frequency (RF) signal; and a receiver coupled to the antenna to receive the RF signal via a first pin, the receiver including: an input signal path to communicate the RF signal; a low noise amplifier (LNA) coupled to receive the RF signal via the input signal path and to amplify the RF signal; a capacitor attenuator coupled between the first pin, the LNA, and a second pin and having a controllable capacitance to attenuate the RF signal, wherein the capacitor attenuator comprises a first capacitor array controllable, responsive to a strength of the RF signal, to have a first portion coupled between the first pin and the LNA and a second portion coupled between the first pin and the second pin coupled to an external reference node, and a second capacitor coupled between the LNA and the external reference node; a detection circuit including a detector to detect a zero crossing of the RF signal; and a controller to update a capacitance of the capacitor attenuator and to cause a digital signal processor (DSP) to compensate for the update to the capacitance, responsive to the zero crossing.
A radio receiver system includes an antenna that captures a radio frequency (RF) signal. The receiver, connected to the antenna, amplifies the RF signal using a low noise amplifier (LNA). A capacitor attenuator, placed between the antenna's input pin and the LNA, reduces the RF signal's strength. This attenuator has a controllable capacitance, adjusted based on the RF signal's strength. The attenuator contains a first capacitor array with a portion between the input pin and the LNA, and another portion between the input pin and an external reference node. A second capacitor is placed between the LNA and the external reference node. A detection circuit detects when the RF signal crosses zero. A controller updates the attenuator's capacitance at the zero crossing and signals a digital signal processor (DSP) to compensate for the capacitance change.
2. The system of claim 1 , further comprising a first resistor attenuator coupled to the first pin to attenuate low frequency noise, the first resistor attenuator controllable by the controller based on detection of the low frequency noise, responsive to the zero crossing.
The radio receiver system described above, which has an antenna, receiver, LNA, capacitor attenuator, zero-crossing detection, and DSP compensation, also includes a first resistor attenuator connected to the antenna's input to reduce low-frequency noise. The system's controller adjusts this resistor attenuator based on detected low-frequency noise, triggered by the zero-crossing detection.
3. The system of claim 2 , further comprising a second resistor attenuator to attenuate the RF signal when the RF signal is greater than a predetermined threshold, wherein the second resistor attenuator is disabled when the RF signal is less than the predetermined threshold.
The radio receiver system described above, including the antenna, receiver, LNA, capacitor attenuator, zero-crossing detection, DSP compensation, and the first resistor attenuator for low frequency noise, incorporates a second resistor attenuator. This second attenuator activates when the RF signal exceeds a threshold, further reducing the RF signal strength. It deactivates when the RF signal is below the threshold.
4. The system of claim 1 , wherein the controller is implemented within the DSP.
In the radio receiver system described above, which includes an antenna, receiver, LNA, capacitor attenuator, zero-crossing detection, and DSP compensation, the controller responsible for updating the attenuator's capacitance and signaling the DSP is implemented within the digital signal processor (DSP) itself.
5. A method comprising: receiving a radio frequency (RF) signal in a radio receiver and amplifying the RF signal in a low noise amplifier (LNA); detecting a level of the RF signal and a zero crossing of the RF signal in detector circuitry of the radio receiver; at the zero crossing of the RF signal, updating an attenuation level of an attenuator of the radio receiver based on the detected level of the RF signal; and responsive to the detected level of the RF signal, controlling a first portion of a first capacitor array coupled between a first terminal of the radio receiver and the LNA to be a first value and controlling a second portion of the capacitor array coupled between the first terminal and a second terminal of the radio receiver coupled to an external reference node to be a second value, and further controlling a second capacitor array coupled between the LNA and the external reference node.
A method for receiving radio signals includes amplifying the RF signal using a low noise amplifier (LNA) within a receiver. The method detects the RF signal's strength and its zero-crossing point using detector circuitry in the receiver. At the zero-crossing point, the method updates the receiver's attenuator level based on the RF signal strength. Based on this detected RF signal strength, the method adjusts a first portion of a capacitor array between a receiver terminal and the LNA to a specific value. It also controls a second portion of the capacitor array, situated between the receiver terminal and an external reference node connected to another receiver terminal, to a second value. A second capacitor array, coupled between the LNA and the external reference node, is controlled as well.
6. The method of claim 5 , further comprising, at the zero crossing of the RF signal, sending a signal to a digital signal processor (DSP) of the radio receiver to enable digital compensation for the attenuation level update.
The method for receiving radio signals described above, which includes amplifying the RF signal, detecting the RF signal's strength and zero-crossing, updating the attenuation level, and controlling capacitor arrays, further includes sending a signal to the radio receiver's digital signal processor (DSP) at the RF signal's zero crossing to enable digital compensation for the attenuation level change.
7. A system comprising: an input terminal to receive a radio frequency (RF) signal; an input signal path to communicate the RF signal; a low noise amplifier (LNA) coupled to receive the RF signal via the input signal path and to amplify the RF signal; a capacitor attenuator coupled to the input terminal to attenuate the RF signal by a controllable amount and having a first portion controllable to include a used part configured on the input signal path and an unused part coupled between the input signal path and an AC reference node, and a second portion coupled between the LNA and the AC reference node, wherein a capacitance of the first and second portions is responsive to a strength of the RF signal; a detection circuit including a detector to detect a zero crossing of the RF signal; and a controller to update a capacitance of the capacitor attenuator, responsive to the zero crossing.
A radio receiver system receives a radio frequency (RF) signal and directs it through an input signal path. A low noise amplifier (LNA) amplifies the RF signal from this path. A capacitor attenuator connected to the input controls the RF signal strength. The capacitor attenuator features a first part with controllable segments: a "used" segment in the signal path, and an "unused" segment connected between the signal path and an AC reference point. The attenuator also has a second part between the LNA and the AC reference. The capacitances of these parts are responsive to the RF signal strength. A detector circuit detects when the RF signal crosses zero. A controller updates the capacitor attenuator's capacitance when this zero crossing occurs.
8. The system of claim 7 , further comprising a second terminal to couple to the AC reference node, wherein the unused part of the first portion is coupled to the second terminal, and further comprising an external capacitor coupled between the second terminal and the AC reference node.
The radio receiver system described above, including the input, LNA, capacitor attenuator with controllable segments, zero-crossing detection and controller, includes a second terminal connected to the AC reference node. The "unused" part of the first capacitor segment is coupled to this second terminal. An external capacitor is also connected between the second terminal and the AC reference node.
9. The system of claim 7 , wherein the input signal path is coupled to communicate the RF signal to a first input terminal of the LNA, and the AC reference node is coupled via a capacitor to a second input terminal of the LNA.
The radio receiver system described above, including the input, LNA, capacitor attenuator with controllable segments, zero-crossing detection and controller, has its input signal path connect to the LNA's first input terminal. The AC reference node is connected via a capacitor to the LNA's second input terminal.
10. The system of claim 7 , further comprising a control logic to receive at least one control signal and to provide the at least one control signal to control at least the first portion of the capacitor attenuator upon the zero crossing of the RF signal.
The radio receiver system described above, including the input, LNA, capacitor attenuator with controllable segments, zero-crossing detection and controller, incorporates a control logic unit. This unit receives control signals and uses them to control at least the first section of the capacitor attenuator at the zero crossing point of the RF signal.
11. The system of claim 7 , wherein the first portion of the capacitor attenuator includes a plurality of capacitors, each having a first terminal coupled to the input terminal and a second terminal coupled to a switching node, the switching node to couple to the LNA via a first switch and to couple to the AC reference node via a second switch.
The radio receiver system described above, including the input, LNA, capacitor attenuator with controllable segments, zero-crossing detection and controller, has the first part of its capacitor attenuator consisting of multiple capacitors. Each capacitor has one terminal attached to the RF input, and the other terminal connected to a switching node. This node connects to the LNA via a first switch and to the AC reference node via a second switch.
12. The system of claim 11 , wherein the first switch is controlled via a first control signal and the second switch is controlled via a second control signal.
In the radio receiver system described above, including the input, LNA, capacitor attenuator with multiple capacitors and switching nodes, zero-crossing detection and controller, the first switch (connecting to the LNA) is controlled by a first control signal, and the second switch (connecting to the AC reference node) is controlled by a second control signal.
13. The system of claim 7 , further comprising a first resistor attenuator coupled to the input terminal to attenuate low frequency noise.
The radio receiver system described above, including the input, LNA, capacitor attenuator with controllable segments, zero-crossing detection and controller, incorporates a first resistor attenuator attached to the RF input, designed to reduce low-frequency noise.
14. The system of claim 13 , further comprising a second resistor attenuator coupled to the input terminal to further attenuate the RF signal when the RF signal is greater than a predetermined threshold.
The radio receiver system described above, including the input, LNA, capacitor attenuator with controllable segments, zero-crossing detection and controller and a first resistor attenuator, includes a second resistor attenuator connected to the input. This second attenuator reduces the RF signal's strength further if the RF signal exceeds a defined threshold.
15. The system of claim 14 , wherein the second resistor attenuator is disabled when an attenuation range of the capacitor attenuator is sufficient to fully attenuate the RF signal, wherein the RF signal is less than the predetermined threshold.
In the radio receiver system including the input, LNA, capacitor attenuator, first resistor attenuator for low frequency noise, and a second resistor attenuator for high signal levels, the second resistor attenuator is disabled when the capacitor attenuator is sufficient to fully reduce the RF signal, meaning the RF signal is below the predetermined threshold.
16. The system of claim 14 , wherein the controller is to cause a digital signal processor (DSP) to compensate for the update to the capacitance.
In the radio receiver system including the input, LNA, capacitor attenuator, first resistor attenuator, and second resistor attenuator, the controller updates the capacitance of the capacitor attenuator and also signals a digital signal processor (DSP) to compensate for this change in capacitance.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 15, 2015
August 15, 2017
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